Apparatus and method for changing unwinding units in a wrapping machine, and unwinding apparatus

ABSTRACT

An apparatus associated with a wrapping machine includes at least one unwinding unit for the wrapping machine for wrapping a load with a film, and shuttles that are movable along a path and suitable for receiving and supporting an unwinding unit to be replaced and to be dismantled from the wrapping machine, or a new unwinding unit to be mounted on the wrapping machine. The shuttles operate along a substantially horizontal operating direction to dismantle and receive from the wrapping machine an unwinding unit to be replaced or to transfer and mount on the wrapping machine a new unwinding unit. The apparatus includes a supporting unit fixed to the wrapping machine and arranged to be coupled to, and supported by, the unwinding unit, the unwinding unit including a first coupling device, and the supporting unit including a second coupling device, the first coupling device and the second coupling device being mutually coupled or uncoupled along the operating direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/238 497 filed Feb. 12, 2014. application Ser. No. 14/238,497 is a §371 National Stage of PCT International Application No.PCT/IB2012/054125. PCT/IB2012/054125 claims priority to IT ApplicationNo. MO2011A000211 filed Aug. 16, 2011 and MO2011A000312 filed Dec. 1,2011. The entire contents of these applications are incorporated hereinby reference.

BACKGROUND OF THE INVENTION

The invention relates to machines and methods for wrapping a load with afilm of extensible synthetic plastic material. In particular, theinvention relates to an apparatus and a method for automaticallychanging a film unwinding unit that is mounted on a wrapping machine.The invention further relates to a wrapping machine including suchapparatus and to a film unwinding apparatus removably associated with awrapping machine and a wrapping machine including such unwindingapparatus.

BRIEF DESCRIPTION OF THE PRIOR ART

Known wrapping machines generally include an unwinding unit supporting areel from which synthetic plastic film is unwound to be wrapped aroundthe load to form a series of strips or bands with helical or coiledtrend, by virtue of the combination of the movement in the verticaldirection of the unwinding unit and the reciprocal rotation between thelatter and the load. The latter is typically composed of one or moreproducts grouped and arranged on a bed or pallet.

In the wrapping machines provided with a rotating table for supportingthe load, the latter is rotated around a vertical wrapping axis, whereasthe unwinding unit is moved vertically with a reciprocating motion alonga fixed column of the machine.

In the wrapping machines with a horizontal rotating ring or rotatingarm, the load remains stationary during wrapping, while the unwindingunit is moved with respect to the latter, both rotating around thevertical wrapping axis and translating along the latter. For thispurpose, the unwinding unit is fixed to a ring or an arm that isrotatably supported by a fixed structure of the machine and so as torotate around the load.

In vertical rotating ring wrapping machines, the load is movedhorizontally through the ring, while the unwinding unit rotates with thering around a horizontal wrapping axis.

The unwinding unit typically includes a pair of pre stretching rollersarranged for unwinding the film from the reel and pre-stretching orelongating the film, and one or more diverting or idle rollers that arearranged for diverting the film towards the load. By suitably adjustingthe difference in the rotation speeds of the pre-stretching rollers, itis possible to pre-stretch by a defined amount or percentage the filmexiting from the unwinding unit. By adjusting the rotation speed of thepre-stretching rollers, it is also possible to vary the unwinding speedof the film from the reel, i.e., the speed at which the film leaves theunwinding unit.

The unwinding unit generally includes an electric motor capable ofrotating one of the two pre-stretching rollers that acts as a driving(master) roller and that drives, through a transmission/reduction unit,the other pre-stretching roller acting as a driven roller or slave.

In this manner, a preset transmission ratio is imposed between the quickroller and the slow roller, as a function of the pre-stretch that it isdesired to obtain on the film. Unwinding units including two distinctelectric motors are also known for independently driving the twopre-stretching rollers.

In the case of exhaustion, breaking, damage or jamming of the film, thereel has to be replaced with a new reel. Such replacement operation isgenerally carried out manually by an operator who, after stopping themachine and locating the unwinding unit at a suitable height from theground, proceeds to remove the reel to be replaced from thecorresponding supporting shaft and then inserts and locks a new filmreel. At this point, it is necessary to remove from the new reel aninitial portion of the film and wind it around the pre-stretching andidle rollers according to the required wrapping path, up to grippingpliers that are fixed to the weight-bearing structure of the machine andintended to keep the film in the initial wrapping step around theproduct.

These manual interventions, in addition to being heavy for the operator,require the presence and availability of the operator near the machine,in the case where the operator is absent or engaged in other activities,the replacement procedure can require machine downtimes that are alsorelatively long, with consequent reduction of the productivity of themachine.

In order to obviate such a drawback, apparatuses for replacing the reelsare known, including a carriage bearing one or more new reels and thatis movable away from or towards the machine. During reel replacement,the replacement carriage is near the machine for receiving the exhaustedreel and releasing the new reel which is automatically inserted on thesupporting shaft (swift) of the unwinding unit. In this way, reelreplacement can be carried out automatically.

However, the above-mentioned apparatuses have the drawback that theyrequire the manual winding of the initial film flap of the new reelaround the rollers of the unwinding unit in order to allow the properstart of the machine. This preliminary winding operation, which iscarried out manually, is laborious and slow, and determinates anincrease of the time required for the reel replacement.

Apparatuses that are provided with devices for automatically carryingout the above-mentioned preliminary winding operation are also known.

However, such apparatuses, while allowing the replacement of the reel ina completely automatic manner, without the need for a manualintervention by an operator, are not very reliable. In particular, theydo not ensure that the preliminary winding operation at each reelreplacement is properly executed.

Apparatuses that are suitable for replacing the whole unwinding unitmounted on the wrapping machine are also known. In this case, once thefilm is finished, the unwinding unit that is mounted on the machine isremoved from the machine, located on suitable supports, and replaced byan unwinding unit that is provided with a new film reel with the initialfilm flap already properly wound around the pre-stretching and idlerollers. The replacement unwinding unit is also located on a supportthat is adjacent to the machine so as to be able to be hooked onto andremoved from the wrapping machine.

A drawback of the above-mentioned apparatuses is that the supports ofthe unwinding units have to be located adjacent to the machine to allowfor the replacement of the unwinding units. In such positions, thesupports, due to their overall dimensions, can considerably limit theeffectiveness of the wrapping machine, in particular, the mounting ofoptional units and/or optional accessories. Such a drawback isparticularly apparent in the case where the machine includes two or moreunwinding units, and therefore a higher number of supports.

Furthermore, considering the proximity within the working zone of thewrapping machine, for safety reasons it is necessary to stop the machineto allow operators access to the support while inserting or removing theunwinding units. Such operations necessarily involve stopping themachine, thus reducing its productivity.

Another drawback is that mounting and dismantling the unwinding unitfrom the wrapping machine is very laborious and complex, since theprocedure requires the movement of the wrapping machine, in particularof the ring or the rotating arm that supports the winding unit.Furthermore, the coupling device, which is necessary to fix theunwinding unit to the wrapping machine, is complex and expensive. Thecoupling device, besides allowing a reversible coupling for the mountingand dismantling, must also ensure firm and reliable locking of theunwinding unit to the machine, even for high rotation speeds of themachine.

Each unwinding unit includes, in addition to the film reel and thepre-stretching and unwinding rollers, the motor(s) necessary for drivingthe pre-stretching rollers. The unwinding unit further includes suitableconnectors, which engage on complementary connectors that are providedon the wrapping machine to receive supply energy and control signals forthe driving motors of the pre-stretching rollers.

A drawback of such replacement systems is that the above-mentionedunwinding units are equipped with film reel, motors, and pre-stretchingand winding rollers which are very expensive and which necessitate atleast two unwinding, units in order to allow for rapid replacement and adecreased downtime of the wrapping machine.

SUMMARY OF THE INVENTION

An object of the invention is to improve the known apparatuses andmethods to replace an unwinding unit in a wrapping machine.

Another object is to provide an apparatus and a method that allows anautomatic, rapid, and efficient replacement of an unwinding unit in awrapping machine, in particular of the type with a rotating ring or arm,or of the rotating platform type.

A further object is to obtain an apparatus that is compact and hasreduced dimensions, such as not to limit in any manner the operation ofthe wrapping machine and to allow the mounting of optional units and/oraccessories.

Another object is to make an apparatus that allows automatic replacementof a plurality of unwinding units, without requiring the intervention ofoperators.

Still another object is to provide an apparatus and a method that allowsthe unwinding unit to be reversibly mounted and locked to the wrappingmachine.

A still further object is to make a wrapping machine that allowsreplacing an unwinding unit in an automatic, rapid, and efficientmanner.

Another object is to provide a film unwinding apparatus that isremovably associated with a wrapping machine and that allows replacingan unwinding unit in an automatic, rapid, and efficient manner.

Another further object is to provide an unwinding apparatus thatperforms different types of winding of the film around the rollers whichunwind and pre-stretch the film.

Still another object is to provide an unwinding apparatus that iscompact and inexpensive.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be better understood and implemented with referenceto the attached drawings, that illustrate some embodiments thereof byway of non-limiting example, in which:

FIG. 1 is a perspective view of an apparatus for replacing an unwindingunit associated with an horizontal rotating ring wrapping machine;

FIG. 2 is a top plan view of the apparatus and the wrapping machine ofFIG. 1 in combination with a load to be wrapped in different successivepositions;

FIG. 3 is a front view of the apparatus and the wrapping machine of FIG.1 in a wrapping procedure of a load with a film;

FIGS. 4 to 10 are complete or partial perspective views of the apparatusand the wrapping machine of FIG. 1 in successive operating steps,respectively, of a replacement procedure of an unwinding unit;

FIG. 11 is a fragmentary and partial perspective view of the apparatusof FIG. 1, particularly illustrating shuttles that are movable along aguide and supporting an unwinding unit;

FIG. 11a is a partial and enlarged view of the apparatus of FIG. 11,illustrating an upper portion of the unwinding unit;

FIG. 12 is a partial and enlarged perspective view of the wrappingmachine of FIG. 1, illustrating in particular the unwinding unit and acorresponding supporting unit mutually spaced apart;

FIG. 12a is a partial and enlarged view of the apparatus of FIG. 12,illustrating in particular the supporting unit;

FIGS. 13 and 14 are plan views from the top and bottom, respectively, ofthe unwinding unit and the supporting unit of FIG. 12;

FIGS. 15 and 16 are perspective views from the bottom and top,respectively, of a first driven shuttle of the apparatus of FIG. 1 witha transfer device in a closed position;

FIG. 17 is a side view of the first driven shuttle of FIG. 15;

FIG. 16 is a top perspective view of the first driven shuttle of FIG.15, with the transfer device in an extended position;

FIG. 19 is a top plan view of a version of the apparatus for replacingunwinding units of the invention, which is associated with a rotatingplatform wrapping machine;

FIG. 20 is a top plan view of another version of the apparatus forreplacing unwinding units of the invention, which is associated with arotating platform wrapping machine with a tilted column;

FIGS. 21 and 22 are perspective views from the bottom and top,respectively, of a second driven shuttle of the version of the apparatusof FIG. 20 with respective transfer devices in a closed condition;

FIG. 23 is a top plan view of the second driven shuttle of FIG. 21;

FIG. 24 is a top perspective view of the second driven shuttle of FIG.21, with respective transfer devices in an extended condition;

FIG. 25 is a perspective view of an apparatus of the inventionassociated with a wrapping machine provided with two rotating arms;

FIG. 26 is a partial bottom perspective view of the unwinding apparatusof the invention associated with a wrapping machine and including anunwinding unit and a supporting unit in a detached configuration;

FIG. 27 is a top perspective view of the unwinding apparatus of FIG. 26in an assembled configuration;

FIG. 28 is a fragmentary and partial perspective view of the unwindingunit of the apparatus of FIG. 26;

FIG. 29 is a partial and enlarged perspective view of the supportingunit of the apparatus of FIG. 26, fixed to a rotating ring of thewrapping machine;

FIGS. 30 and 31 are plan views from the top and the bottom,respectively, of the unwinding unit and the supporting unit of theapparatus of FIG. 26 in a mounting step;

FIGS. 32 and 33 are plan views from the top and side, respectively, ofthe unwinding apparatus of the invention associated with a horizontalrotating ring wrapping machine;

FIG. 34 is a perspective view of the apparatus and the machine of FIG.32, in which some details have been removed, and in a replacement stepof an unwinding unit;

FIG. 35 is a fragmentary and partial perspective view of an unwindingunit of a version of the unwinding apparatus of FIG. 26;

FIG. 36 is a partial and enlarged perspective view of the supportingunit, fixed to a rotating ring of the wrapping machine, of the versionof the unwinding apparatus of FIG. 35;

FIG. 37 is a partial and enlarged perspective view of the unwindingapparatus of FIGS. 35 and 36, illustrating in particular first andsecond transmissions;

FIG. 38 is a plan view of another version of the unwinding apparatusassociated with a rotating table wrapping machine;

FIG. 39 is a perspective view of a further version of the unwindingapparatus of the invention, associated with a double rotating armwrapping machine.

DETAILED DESCRIPTION

With reference to the FIGS. 1 to 3, there is illustrated the apparatus Iaccording to the invention, arranged for changing unwinding units 50 of,and associated with a wrapping machine 10 for wrapping a load L with afilm 4 of extensible synthetic plastic material.

The apparatus 1 of the invention includes at least one unwinding unit50, a supporting unit 60 associated with the wrapping machine 10, andshuttles 11, 12 for moving the unwinding unit.

The wrapping machine 10 is, for example, provided with a horizontal ring101, which is rotating around a vertical wrapping axis Z, and which isvertically movable so as to wrap the load L with helical coils or bandsof film 4. The ring 101 is rotatably supported by a sliding frame (notillustrated) that is linearly movable along a vertical direction that issubstantially parallel to the above-mentioned wrapping axis Z. On thering 101, a supporting unit 60 is fixed, to which an unwinding unit 50of the film 4 can be reversibly coupled. The ring 101 and the slidingframe act as a first movement mechanism 100 arranged for moving thesupporting unit 60 and the unwinding unit 50 associated therewith withrespect to the load L.

The unwinding unit 50, described more in detail below, includes a reel 3of film 4 and rollers 55, 56, 57 arranged for unwinding andpre-stretching the film 4.

The unwinding unit 50 further includes a first coupling device 58arranged to engage a second coupling device 68 provided on thesupporting unit 60; the first coupling device 58 and the second couplingdevice 68 are mutually coupled or uncoupled along a substantiallyhorizontal operating direction T, as better explained below.

The apparatus 1 includes shuttles 11, 12 suitable to house at least oneunwinding unit 50 to be replaced and dismantled from the wrappingmachine 10, and/or suitable for supporting at least one new orreplacement unwinding unit 50 to be mounted on the wrapping machine 10.The shuttles 11, 12 move along the substantially horizontal operatingdirection T so as to disconnect from the wrapping machine 10, andtherefore receive, an unwinding unit 50 to be replaced, and transfer andmount a new unwinding unit 50 on the wrapping machine 10, when thelatter is located in a replacement configuration G.

The shuttles 11, 12 include a transfer device 15 suitable for receivingand supporting at least one unwinding unit 50, and movable between aretracted position D1 and an extended position D2 along the operatingdirection T so as to allow the shuttles 11, 12 selectively to dismantleand receive an unwinding unit 50 to be replaced or transfer and mount anew unwinding unit 50.

The operating direction T along which the transferring device 15 ismoved is substantially radial to a circular wrapping trajectory of thefilm 4 around the load L.

The shuttles 11, 12 are also movable along a path P between a firstoperating position F1 in which they dismantle and receive from thewrapping machine 10 an unwinding unit 50 to be replaced (FIGS. 4, 5, 6),a second operating position F2 in which they transfer and assemble a newunwinding unit 50 on the wrapping machine 10 (FIGS. 7, 8, 9), and anon-operating or inactive position N1 in which they are outside aworking zone W of the wrapping machine 10 in order to not interfere withthe operation of the machine (FIGS. 1, 2, 3, 10).

To this aim, the shuttles 11, 12 include an actuator 19 that is able tomove the shuttles 11, 12 along the path P.

The shuttles 11, 12 can further include breaks to stop the shuttles 11,12 at least in the operating positions F1, F2 and in the non-operatingposition N1.

The operating direction T is transverse, in particular orthogonal, tothe path P.

The shuttles 11, 12 include at least one shuttle provided with arespective actuator 19 for movement along the path P and arranged forsupporting at least one unwinding unit 50.

Preferably, the shuffles include a plurality of shuttles 11, 12connectable to one 10 another so as to form at least one convoy 5 ofshuttles. At least one shuttle of the plurality of shuttles is providedwith an actuator 19 to move the convoy 5. Each shuttle includes atransfer device 15 for supporting and moving at least one unwinding unit50.

With reference to FIGS. 1. to 10, in the embodiment illustrated only byway of non-limiting example, a pair of shuttles 11, 12 are provided,each of which are arranged for receiving a respective unwinding unit 50and provided with respective transfer device 15. At least one of the twoshuttles, a so-called driving shuttle 12, is provided with an actuator19 that allows for the controlled movement thereof (at least forposition and speed) along the path P. The remaining shuttle 11, which isnot provided with an actuator 19, a so-called driven shuttle 11, isinterconnected to the driving shuttle 12. The driving shuttle 12 and thedriven shuttle 11 are mutually connectable to form a convoy 5 ofshuttles that is movable along the path P.

In a non-illustrated embodiment of the apparatus, the shuttles includetwo or more driving shuttles 12.

In a further embodiment of the apparatus, which is not illustrated, theshuttles include a driving shuttle 12 and a plurality of driven shuttles11 connected thereto to form a convoy of shuttles suitable for housing aplurality of new unwinding units 50 to be then mounted on the wrappingmachine to allow the latter to operate in a completely automatizedmanner, without intervention of operators, for prolonged work shifts.

In a still another embodiment of the apparatus of the invention which isnot illustrated, only one shuttle is provided with an actuator andtransfer device suitable for receiving and supporting one or moreunwinding units 50. In another further version, a plurality of drivingshuttles 12 and a plurality of driven shuttles 11 mutually connected soas to form a plurality of convoys 5 are provided.

Each shuttle 11, 12 includes a hook for connection with at least oneadjacent shuffle to form a convoy of shuttles. The hook can be fixed,for example, screwable brakets or plates, or movable, in particular,selectively actuatable in order to engage or disengage with a hook of anadjacent shuttle so as to mutually connect or disconnect the shuttlesand form or dismantle, respectively, a convoy of shuttles.

The apparatus includes a guide 2 for slidably supporting the shuttles11, 12 along the path P. The guide 2 substantially includes a beam, inparticular with a closed cross section, to which the shuffles 11, 12 areconnected, and along which they can slide.

The guide 2 passes through the working zone W of the wrapping machine 10and is substantially rectilinear and parallel to an advancing directionV of the load L in the wrapping machine 10.

Alternatively, the guide 2 can be curved and include at least onerectilinear portion at least at the two operating positions F1, F2.

As illustrated in the FIGS. 15 to 18, the shuttle 11 devoid of theacutator, the so-called driven shuttle 11, includes a carriage 13provided with sliding wheels 14 and configured to engage and slide onthe guide 2. The transfer device is slidably connected to the carriageBand includes a transfer platform 15 that is fixed by telescopic guides18 to end portions of the carriage 13 so as to be movable between theretracted position D1 and the extended position D2 along the operatingdirection T.

An actuator 16 is provided for moving the transfer platform 15 along theoperating direction T. The actuator 16 includes, for example, apneumatic or electric linear actuator.

The transfer platform is provided with at least on stop 17 arranged forengaging with the unwinding unit 50 when the latter is located on theplatform and to prevent undesired movements thereof in a plane parallelto the above-mentioned platform and orthogonal to the wrapping axis Z.The stops 17 include, for example, a plurality of pins suitable toengage respective holes provided on a lower portion of each unwindingunit 50.

The shuttle 12 provided with an actuator, the so-called driving shuttle,is substantially identical to the driven shuttle 11 except that it isprovided with the actuator 19 that allows movement thereof along theguide 2.

The actuator 19 includes, for example, an electric motor fixed to thecarriage 13, which rotate a gearwheel engaged with a rack fixed to theguide 2.

Alternatively, the electric motor of the actuator 19 can drive a pulleyor a gearwheel that is coupled to fixed belt or chain transmissionsystems of the guide 2 so as to move the first driving shuttle 12.

Still alternatively, the actuator of the driving shuttle 12 can includea coupling device for connection to belt or chain transmission systemsmovable along the path P by a motor, for example an electric motor,which is associated with the guide 2. The actuator can be activated ordeactivated for connecting or disconnected the first driving shuttle 12to/from the transmission systems and to enable the shuttle to move orstop.

With particular reference to FIGS. 12 to 14, each unwinding unit 50includes a supporting structure 51 suitable for supporting at least onereel 3 of film 4, and rollers 55, 56, 57 suitable for unwinding andpre-stretching the film. The supporting structure 51 includes, inparticular, an upper portion 52 and a lower portion 53 formed by platesinterconnected and spaced apart by a plurality of cross beams 54, Thereel 3 of film 4, a pair of pre-stretching rollers 55, 56 and one ormore diverting or idle rollers 57 are rotatably connected to the upper52 and lower 53 plates. The pre-stretching rollers 55, 56 are rotated bya driving device provided on the supporting unit 60. The unwinding unit50 is further provided with gripping device 59 suitable for retaining aninitial flap of film 4 that is unwound from the reel 3 and wound aroundthe pre-stretching 55, 56 and idle 57 rollers. The so-retained initialflap can be easily gripped by further gripping devices of a known typethat are mounted on the wrapping machine 10.

As set forth above, the unwinding unit 50 includes a first couplingdevice 58 arranged for engaging with a second coupling device 68 of thesupporting unit 60, the first coupling device 58 and the second couplingdevice 68 being mutually coupled or uncoupled along the operatingdirection T, which is substantially horizontal, transverse to the pathP, and substantially radial with respect to the wrapping axis Z.

The first coupling device includes one or more rails 58, for examplefour, slidably inserted into, and engaged with, respective seats 68 ofthe second coupling device. The rails 58 have, for example, a T-shapedsection, and have a front portion 58 a that is tapered to allow easyinsertion and proper centering and positioning in the corresponding seat68 (FIG. 11a ). The seat is provided with horizontal and vertical idlewheels 69, to allow for the sliding and centering of the respective rail58 (FIG. 12a ). The seats 68 act as self-centering sliding blocks forthe respective rails 58.

The first coupling device 58 is associated with an upper portion 52 ofthe supporting structure 51, while the second coupling device 68 isassociated with a lower portion 63 of the supporting unit 60, inparticular, the rails 58 are fixed to an outer face of the upper plate52, while the seats 68 are fixed to a respective lower plate 63 of thesupporting unit 60.

The seats 68 are provided with abutments (not shown), which stop thefurther insertion and sliding of the rails 58, to stop the unwindingunit 50 in a coupling position B with respect to the supporting unit 60.

With reference to the configuration of apparatus and ring wrappingmachine set forth in the FIGS. 1 to 14, the first coupling device 58 isinsertable in the second coupling device 68 up to the coupling positionB, in which the supporting unit 60 is engaged with and completelysupported to the unwinding unit 50 along the operating direction T andwith the advancing direction directed from rotational axis (the wrappingaxis Z of the unwinding unit 50 around the load L) outwardly, i.e. witha direction that is in accordance with a centrifugal force acting on theunwinding unit 50 when the latter rotates around the load L. Owing tothe configuration of the coupling device 58, 68, therefore, it is thesame centrifugal force that keeps the unwinding units 50 properlyassembled and connected in the coupling position B to the supportingunit 60. In other words, during the operation of the wrapping machine,it is the rotation of the ring 101 that prevents the unwinding unit 50from accidentally disengaging and being disconnected from the supportingunit, i.e. from the machine, thus considerably increasing the safety ofthe machine.

Owing to the apparatus of the invention it is thus possible to mount andlock the unwinding unit to the wrapping machine in a reversible, safe,and reliable manner.

For greater safety, a locking device 179 can also be provided which isarranged for locking the unwinding unit 50 to the supporting unit 60 inthe coupling position B. The locking device 179 includes a pair oflocking pins 171 linearly driven by respective electro-magnets 172 andarranged to engage in corresponding openings 173 arranged on the upperplate 52 of the unwinding unit 50 to lock the reciprocal movement of theunwinding unit 50 with respect to the supporting unit 60 in theoperating direction T, in particular in a disconnected direction.

With reference to FIG. 12 a, the driving assembly of the supporting unit60, which is arranged to rotate the pre-stretching rollers 55, 56 of theunwinding unit 50, includes a first flexible element 75, for example afirst toothed belt 75, and a second flexible element 76, for example asecond toothed belt 76, arranged to be abutted and engaged by a firstcoupling pulley or gearwheel 77 of the first pre-stretching roller 55and by a second coupling pulley or gearwheel 78 of the secondpre-stretching roller 56. The toothed belts 75, 76 of the drivingassembly can be driven by at least one motor arranged on the supportingunit 60 or located on a frame of the wrapping machine and connected tothe driving assembly by motion transmission systems of a known type.

Alternatively, the driving motor or motors of the pre-stretching rollers55, 56 can be provided directly on the unwinding unit, the supportingunit being in this case not provided with a driving assembly andoptionally provided with an electrical power supply for theabove-mentioned motors. Versions of the apparatus with this type areillustrated in the FIGS. 19 to 25 described herein below.

FIGS. 1 to 10 illustrate successive steps of a replacement or changeprocedure of an unwinding unit 50 to be replaced, mounted on board ofthe wrapping machine 10, with a new or replacement unwinding unit 50located on the shuttle means 11, 12.

In an initial step, the shuttles 11, 12 from the inactive position N1,outside the working zone W of the wrapping machine 10 to allow the freeoperation of the machine during the wrapping of the load, are moved inthe first operating position F1 within the working zone W (FIG. 4). Inthe first operating position F1 the free shuttle, i.e. not provided witha new or replacement unwinding unit 50 (the driven shuttle 11 in theillustrated example) is precisely under the rotating ring 101, thetransfer device 15 being in the extended position D2 to receive theunwinding unit 50 to be replaced. The machine is arranged in thereplacement configuration G with the rotating ring 101 verticallylowered to rest the unwinding unit 50 to be replaced on the platform ofthe transfer device 15 of the driven shuttle 11 (FIG. 5). The stop 17engages the unwinding unit 50 to be replaced so that the movement of theplatform of the transfer device 15 in the retracted position D1 allowsthe unwinding unit 50 to be replaced from the supporting unit 60 anddisengaged and dismantled from the rotating ring 101 (FIG. 6). Thelocking device 179 is disengaged from the unwinding unit 50 to bereplaced to allow the first coupling device 58 sliding in the operatingdirection T, from the outside inwardly with reference to the rotatingring 101, and disengaging from the second coupling device 68.

Since in the retracted position D1 of the Shuttles 11, 12, the unwindingunit 50 to be replaced is disconnected and spaced apart from thesupporting unit 60, the shuttles 11, 12 can be moved in the secondoperating position F2, at which the shuttle provided with unwindingunits 50 (the driving shuttle 12 in the illustrated example) is at thesupporting unit 60 (FIG. 7), At this point, the transfer device 15 ofthe driving shuttle 12 is moved to the extended position D2 to mount thenew unwinding unit 50 on the supporting unit 60 (FIG. 8). Moreprecisely, the first coupling device 58, i.e., rails, is slidablyinserted in the second coupling device 68, i.e., seats with rollers. Inthe extended position D2 of the transfer device 15, the unwinding unit50 is in the coupling position B with respect to the supporting unit.The locking device 179 can thus be driven for locking the unwinding unit50 to the supporting unit 60.

At this point, the rotating ring 101 is vertically moved so as todisengage the unwinding unit 50 from the stop 17 of the driving shuttle12. The shuttles 11, 12 are thus moved simultaneously with the rotatingring 101 along the path P, from the second operating position F2 to theinactive position N1, outside the working zone to allow the wrappingmachine carrying out the wrapping cycles of the load.

Owing to the apparatus of the invention, it is thus possible toautomatically, rapidly and efficiently replace an unwinding unit in awrapping machine, without any interventions by operators.

Furthermore, the wrapping machine provided with the apparatus of theinvention can operate autonomously for a prolonged work shift, withoutthe intervention of operators since the shuttles can support, andtherefore replace, a plurality of unwinding units.

Furthermore, the mounting and dismantling procedure of the unwindingunit on and from the wrapping machine is easy and rapid, and it does notrequire the movement of the rotating ring 101 of the wrapping machine,which only has to be arranged in the replacement configuration G.Consequently, replacement time is reduced.

Another advantage of the apparatus 1 is that the guide 2, which passesthrough the working zone W of the wrapping machine 10 parallel to anadvancing direction V of the load, allows the shuttles 11, 12 to reachthe operating positions F1, F2 for the easy replacement of the unwindingunits 50. The overall dimensions of the machine are reduced compared tothe known wrapping machines that are provided with apparatuses for thereplacement of the film reel or the unwinding unit. Furthermore, in theinactive position N1, the shuttles 11, 12 are external to the workingzone W so as not to limit in any manner the operability of the wrappingmachine, as well as not to prevent the assembling and operation ofoptional units and/or accessories.

FIG. 19 illustrates an embodiment of the apparatus 1 for replacingunwinding units of the invention, associated with a wrapping machine 10of the rotating platform type. In this wrapping machine 10, thesupporting unit 60 is mounted on a first wrapping carriage 201 that isvertically movable along a fixed first column 202. The first wrappingcarriage 201 and the first column 202 act as a second movernentmechanism 200 arranged for moving the supporting unit 60 and theunwinding unit 50 with respect to the load L.

The shuttles 11, 12 are arranged for dismantling and receiving from thewrapping machine 10 an unwinding unit 50 to be replaced, and thentransferring and mounting a new replacement unwinding unit 50 on thewrapping machine 10. The shuttles 11, 12 are movable along the guide 2that defines the path P and which is interposed between the first column202 and the unwinding unit 50 and a first rotating table 203 supportingand rotating the load L. The guide 2 is substantially rectilinear andparallel to an advancing direction V of the load L through the workingarea of the wrapping machine 10.

The unwinding unit 50 differs from the unwinding unit disclosed above inthat it includes, besides the film reel and the pre-stretching and idlerollers, a first motor 255 for rotating pre-stretching rollers. In thisembodiment of the apparatus 10, the supporting unit 60 is not providedwith a mechanical driving assembly for the pre-stretching rollers, butincludes a connection device of a known type and not shown to provide tothe unwinding unit 50 and in particular to the first motor 255, signalsand controls, electric power, pneumatic energy.

The replacement or change procedure of the unwinding unit 50 to bereplaced, mounted on the wrapping machine 10, with the new unwindingunit 50, located on the shuttles 11, 12, is substantially identical tothe procedure described above with reference to the embodiment set forthin the FIGS. 1 to 10. In this case, the supporting unit 60 is mounted onthe wrapping carriage 201 sliding along the first column 202 in thereplacement configuration G to allow the shuttles 11, 12 replacing theunwinding unit 50 to be replaced and mounting the new unwinding unit 50.

FIG. 20 illustrates another version of the apparatus 1 to replaceunwinding units of the invention, associated with a wrapping machine 10of the rotating platform type and provided with a fixed second column302, arranged adjacent to a second rotating table 303 and tiltedrelative to the advancing direction V of the load L through the machine,More precisely, the second column 302 is located in plan view so that avertical plane H passing through a longitudinal axis thereof, andthrough the wrapping axis Z, is tilted by an angle αthat is not a rightangle, relative to the above-mentioned advancing direction V.

The second column 302 slidably supports a second wrapping carriage 301to which the supporting unit 60 for the unwinding unit 50 is fixed.

The second wrapping carriage 301 and the second column 302 act as athird movement mechanism 300 arranged for moving the supporting unit 60and the unwinding unit 50 associated thereto with respect to the load L.

In this embodiment of the apparatus, the guide 2 along which theshuttles slide, is substantially rectilinear and parallel to theadvancing direction V and, is external to the second column 302 and doesnot pass through the working area W of the wrapping machine 10.

The shuttles further include shuttles 21, 22 differing from the shuttlesof the embodiments described before in that the corresponding transferdevices 15 are movable along the operating direction T that is tiltedwith respect to the path P defined by the guide 2 by the same angle α ofthe vertical plane H, in order to allow dismantling and mounting of theunwinding units 50.

In particular, with reference to the FIGS. 21 to 24, the further shuttlethat is not provided with an. actuator, the so-called further drivenshuttle 11, includes a further carriage 23 slidably supporting therespective transferring platform of the transfer device 15 that isfixed, by telescopic guides 16, to tilted end portions of the carriage23 for movement between the retracted position D1 and the extendedposition D2 along the tilted operating direction T. Actuator 16 isprovided for moving the above-mentioned transfer platform 15 along theoperating direction T. The transfer platform is provided with stops 17arranged for engaging the unwinding unit 50 when the latter is locatedon the platform. The further carriage 23 is provided with sliding wheels14 to engage and slide on the guide 2.

The further shuttle provided with an actuator, the so-called furtherdriving shuttle 22, is substantially identical to the further drivenshuttle 21 except that it is provided with an actuator 19 that allowsfor the movement thereof along the guide 2.

The unwinding unit 50 is provided with a pair of second motors 355suitable for separately and independently moving the pre-stretchingrollers, In this embodiment of the apparatus 1, the supporting unit 60is not provided with a mechanical actuator for the pre-stretchingrollers, but it includes a connection device, of a known type and notshown, to provide signals and controls, electric power, pneumatic energyto the unwinding unit 50, and in particular to the second motors 355.

The replacement procedure for the unwinding unit 50 mounted on board ofthe wrapping machine 10, with a new unwinding unit 50 located on theshuttles 21, 22 is substantially identical to the procedure describedabove with reference to the embodiment illustrated in FIG. 19. Thesupporting unit 60 is mounted on the second wrapping carriage 301 thatslides along the second column 302 in the replacement configuration U toallow dismantling and mounting of the unwinding units 50.

It is suitable to point out that the apparatus of the invention can bealso associated with a wrapping machine having a compact platform. Inthis case, the guide, is arranged externally to the working zone W at adistance that allows dismantling/mounting the unwinding units withoutinterfering with the operation of the machine.

FIG. 25 illustrates a further embodiment of the apparatus 1 to replaceunwinding units of the invention, associated with a wrapping machine 10of the double rotating arm type. In this wrapping machine, eachsupporting unit 60 is mounted on a third wrapping carriage 401 that isvertically movable along a respective vertical arm 402 fixed to a rotarycross beam 404 so as to rotate around the wrapping axis Z and the loadL.

The third carriages 401, the vertical arms 402, and the rotary crossbeam 404 act as a fourth movement mechanism 400 arranged for moving thesupporting unit 60 and the unwinding unit 50 with respect to the load L.

To allow the simultaneous replacement of the two unwinding units 50mounted on the two vertical arms 402, the apparatus 1 includes a guide 2including two beams along which respective shuttles 11, 12 move. Theguide is arranged for dismantling from the wrapping machine 10 and forreceiving an unwinding unit 50 to be replaced, and for transferring andmounting a new unwinding unit 50 on the wrapping machine 10. The beamsof the guide 2 are substantially rectilinear, mutually parallel andparallel to an advancing direction V of the load L and arranged at thesides of a supporting and advancing device 403 of the load L.

The unwinding units 50 are provided with a pair of third motors 455 forseparately and independently driving the pre-stretching rollers.

The shuttles 11, 12 are substantially similar to those described above.The shuttles differ from those illustrated in the FIGS. 15 to 18 in thatthey include transfer devices 45 having different dimensions and shape.

In the embodiment illustrated in FIG. 25, the shuttles provided onrespective beams of the guide 2 include a plurality of shuttles 11, 12forming two distinct convoys. In particular, the shuttle means include afirst pair of shuttles 11, 12 (driving shuttle 12 and driven shuttle 11)that firms a convoy 5 of shuttles, and a second pair of shuttles 11, 12(driving shuttle 12 and driven shuttle 11) that forms a further convoy 6of shuttles. Each convoy 5, 6 is drivable in an independent manner alonga respective beam of the guide 2. In this manner, it is possible toprovide up to three unwinding units 50 available for the mounting on themachine, to allow the latter to operate in a completely automatizedmanner, without the intervention of operators, for prolonged workshifts.

The replacement procedure for replacing the unwinding units 50 mountedon the vertical arms 402 of the wrapping machine 10 with the newunwinding units 50 located on the shuttles 11, 12 is substantiallysimilar to the procedure described for the rotating ring wrappingmachine shown in FIGS. 1 to 10. In this case, in the replacementconfiguration G of the wrapping machine 10, the two rotating arms 402are located above the respective guide 2 to allow the shuttles 11, 12 inthe first operating positions to dismantle the unwinding units 50 to bereplaced from the supporting units 60.

With reference to the FIGS. 26 to 34, an unwinding apparatus 30 isillustrated which can be associated with a wrapping machine 10 arrangedfor wrapping or binding a load L with a film 4 of extensible plasticmaterial. The wrapping machine 10 is of the horizontal rotating ringtype, i.e. provided with a horizontal ring 101, which is rotating arounda vertical wrapping axis Z, and which is vertically movable so as towrap the load L with helical strips or bands of film 4 (FIG. 32). Thering 101 is rotatably supported by a frame of the machine, including asliding frame (not illustrated) that is linearly movable along amovement direction that is vertical and substantially parallel to thewrapping axis Z.

The unwinding apparatus 30 includes a supporting unit 60 that is fixedto the ring 101, and an unwinding unit 50 provided with a reel 3 of film4, and which is removably or reversibly coupled to the supporting unit60 in an assembled configuration A (FIG. 27). The ring 101 and thesliding frame act as a movement mechanism 100 arranged for moving theunwinding apparatus 30 with respect to the load L.

The unwinding unit 50 includes rollers 55, 56, 57 arranged for unwindingand pre-stretching the film 4. The rollers include a firstpre-stretching roller 55 and a second pre- stretching roller 56 forunwinding the film 4 from the reel 3 and pre-stretching or elongating itby a preset amount or percentage. The rollers further include one ormore guide or idle rollers 57 for guiding the film 4 from the reel 3 tothe pre-stretching rollers 55, 56 and from the latter towards the load Lto be wrapped.

As illustrated in detail in FIG. 31, the pre-stretching rollers 55, 56and the guide rollers 57 are arranged on the winding unit 50 so as towind the film 4 with an “S” pattern. Such “S” type winding allows thepre-stretching rollers 55, 56 to have a winding angle of the filmgreater than 180°, in particular greater than 270°. Large winding anglesof the film 4 on the pre-stretching rollers 55, 56 optimizes thepre-stretching or elongation operation of the film. In particular, theyallow high pre-stretch values, which limit the reduction in the heightor width of the film hand, and generally provide a better quality offilm 4.

The pre-stretching rollers 55, 56 and the guide rollers 57 can bearranged on the winding unit 50 so as to implement other winding typesof the film 4, for example, of the “W” type.

The supporting unit 60 is provided with a driving assembly 70 to drivethe pre-stretching rollers 55, 56 in the assembled configuration A andin an operating condition of the wrapping machine 10 during the wrappingof the load L. In particular, the driving assembly 70 is configured torotate the first pre-stretching roller 55 and the second pre-stretchingroller 56 in a separated and independent manner.

The unwinding unit 50, as better explained in the description below, canbe easily and quickly dismantled from the supporting unit 60 (typically,in the case of exhaustion or breakage or damage or jamming of the film)and replaced by an identical unwinding unit 50, but provided with a newfilm reel, one initial flap of which is properly wound on the rollersand ready to start the wrapping.

The unwinding unit 50 includes a supporting structure 51 suitable forsupporting the reel 3 of film 4, and the rollers 55, 56, 57. Thesupporting structure 51 includes an upper portion 52 and a lower portion53 formed by respective plates that are interconnected and spaced apartby a plurality of cross beams 54. The reel 3 of film 4, the pair ofpre-stretching rollers 55, 56 and one or more guide or idler rollers 57are rotatably connected to the upper plate 52 and the lower plate 53.

The first pre-stretching roller 55 and the second pre-stretching roller56 are fixed in an adjustable manner to the supporting structure 51 toallow a varying interaxis H thereof (FIGS. 30 and 31). The upper plate52 and the lower plate 53 are provided with respective through slots 52a, 53 a for an adjustable connection of the pre-stretching rollers 54,55.

Therefore, the unwinding apparatus 30 of the invention providesadjustment of the interaxis H between the two pre-stretching rollers 54,55 to carry out an optimal unwinding and pre-stretching of the film 4 asa function of different characteristics of the film and operatingrequirements, such as, for example, the type of the material, thethickness, the height of the film, the diameter of the pre-stretchingrollers, the covering factor of the film, the unwinding speed of thefilm, the pre-stretch percentage, and the dimensions and shape of theload to be wrapped.

The value of the interaxis between the two rollers can be determined bytests and trials.

The unwinding unit 50 is further provided with gripping devices 59 toretain an initial flap of film 4 unwound from the reel 3 and woundaround the pre stretching 55, 56 and guide 57 rollers. The initial flapcan be easily gripped by further gripping devices of a known type thatare mounted on the wrapping machine 10.

The unwinding unit 50 includes a first coupling device 58 arranged toengage a second coupling device 68 of the supporting unit 60, the firstcoupling device 58 and the second coupling device 68 being mutuallycoupled or uncoupled along the operating direction T which issubstantially horizontal.

The first coupling device includes a plurality of rails 58, for example,three, arranged for being slidably inserted in, and engaged with,respective seats 68 of the second coupling device. The seats areprovided with horizontal and vertical idle wheels 69 to allow thesliding and centering of the respective rail 58. In this way, the seats68 act as self-centering sliding blocks for the respective rails 58.

The first coupling device 58 is associated with the upper plate 52 ofthe supporting structure 51, while the second coupling device 68 isassociated with a lower portion 63 of the supporting unit 60. Inparticular, the rails 58 are fixed to an outer face of the upper plate52 while the seats 68 are fixed to a respective lower plate 63 of thesupporting unit 60.

The seats 68 are provided with an abutment (not shown) which stops thefurther inserting and sliding of the rails 58, to stop the unwindingunit 50 in a coupling position with respect to the supporting unit 60.

The first coupling device 58 is insertable into the second couplingdevice 68 up to a complete coupling in the assembled configuration Aalong the operating direction T and with an advancing direction directedfrom the rotating axis (the wrapping axis Z of the unwinding unit 50around the load L) outwardly, i.e. with a direction in accordance withthe centrifugal force acting on the unwinding unit 50 when the latter isrotating around the load L. Owing to the configuration of the couplingdevice 58, 68, it is therefore the same centrifugal force that keeps theunwinding unit 50 properly assembled and connected to the supportingunit 60.

Therefore, the apparatus of the invention allows mounting and lockingthe unwinding unit 50 to the wrapping machine in a reversible and, atthe same time, safe and reliable manner.

For greater safety, a locking device is provided, which is not shown inthe figures, acting transversally to the direction T, in particularvertically, to lock the rails 58 in the seats 68 and, therefore, theunwinding unit 50 to the supporting unit 60 in the assembledconfiguration A.

With particular reference to FIGS. 26 to 34, the driving assembly 70associated to the supporting unit 60 includes motors 81, 82 and a firsttransmission 71 driven by the motors 81, 82 and arranged for engagingand actuating a second transmission 72 of the pre-stretching rollers 55,56.

With particular reference to the FIGS. 28 and 29, the first transmission71 includes a first flexible element 75 and a second flexible element76, for example, a pair of belts with double teeth or a pair of chains,each flexible element 75, 76 being drivable separately and independentlyfrom the motors 81, 82. The second transmission 72 includes a firstcoupling wheel 77 and a second coupling wheel 78, in particular, a pairof pulleys or gearwheels, associated with the first pre-stretchingroller 55 and the second pre-stretching roller 56, respectively. In theassembled configuration A, each flexible element 75, 76 is arranged toengage and rotate the respective coupling wheel 77, 78.

In this way, the motors 81, 81 can rotate the pre-stretching rollers 55,56. The length of the flexible elements 75, 76 is such as to ensure theengagement with the coupling wheels 77, 78 for any value of theinteraxis H of the pre-stretching rollers 54, 55.

Each flexible element 75, 76 is supported and moved by a respective pairof support wheels 74, 79, one of which is idle (idle support wheel 74),and the other of which is motorized (motorized support wheel 79). Thesupport wheels 74, 79 include pulleys or gearwheels. The motorizedsupport wheels 79 are rotated by the motors 81, 82 including at leastone rotating electric motor located on the supporting unit 60 or fixedto the sliding frame of the wrapping machine 10.

In the embodiment illustrated in FIGS. 26 to 34, the motors include afirst motor 81 and a second motor 82 that are fixed to the sliding frameof the wrapping machine and connected to the first transmission 71 by athird transmission 73. The third transmission includes, for example, afirst flexible element 85 and a second flexible element 86, for examplea pair of toothed belts or a pair of chains, driven by the first motor81 and the second motor 82, respectively, and driving, by suitable idleand transmission elements, the respective motorized support wheels 79 ofthe first transmission 71. Such a transmission system is disclosed inthe international patent application W02008/007189.

The two motors 81, 82, while being fixed to the sliding frame and,therefore, not being fixed to the rotating ring 101, can in this waydrive in an independent manner the respective pre-stretching rollers 55,54, thus allowing varying rotation speeds of the latter and, inparticular, the pre-stretch ratio, also during the operation of thewrapping machine.

In a non-illustrated embodiment, the motor of the driving assembly 70includes only one motor arranged on the sliding frame and actuating boththe pre-stretching rollers 54, 55 by the third transmission. In thisembodiment, the third transmission includes known devices to transmitrotation with different speeds to the two pre-stretching rollers 55, 56.

Owing to the unwinding apparatus 30 of the invention, it is thuspossible to rapidly and easily dismantle an unwinding unit 50 to bereplaced (in the case of exhaustion or breakage or damage or jamming ofthe film) and to replace it with an identical unwinding unit 50, butprovided with a new film reel, an initial flap of which is properlywound on the roller and ready to start the wrapping. Since the drivingassembly 70 is provided on the supporting unit 60 fixed to the machine,each unwinding unit 50 (including only the film reel and thepre-stretching and guide rollers) is relatively inexpensive and easy tomake. At the same time, since the above-mentioned unwinding unit 50includes all the pre-stretching and guide rollers around which theinitial film flap retained by the gripping device 59 is wound, theproper automatic start of the wrapping procedure is always ensured.

The pre-stretching rollers 55, 56 and the guide rollers 57 can bearranged to carry out a winding of the film 4 of the so-called “S” typethat provides a winding on the pre-stretching rollers 55, 56 at an anglegreater than 180°, in particular up to and beyond 270°. High windingangles of the film on the pre-stretching rollers 55, 56 optimizes thepre-stretching or elongating operation of the film to provide highpre-stretch values, limiting a height or width reduction of the filmband and, in general, obtaining a better quality of the film.

FIGS. 35 to 37 illustrate a version of the unwinding apparatus 30 of theinvention that differs from the embodiment described above for thetransmission. In fact, the first transmission 91 of the driving assembly70 includes a pair of movable members 95, 96 configured for engaging andmoving a pair of follower members 97, 98 of the second transmission 92associated to respective pre-stretching rollers 55, 56 on the unwindingunit 50. In particular, the first transmission 91 includes a firstmovable element 95 and a second movable element 96 driven by the motorand arranged to drive a first follower member 97 and a second followermember 98, respectively, of the second transmission 92.

Each movable element 95, 96 includes a bush of a substantiallycylindrical shape, that can be rotated around a respective longitudinalaxis by the motor and provided with a transverse seat 95 a, 96 a, inparticular a substantially diametric through seat, arranged for slidablyreceiving a coupling portion of the respective follower member 97, 98.

Each follower member 97, 98 includes an eccentric pin or a crank fixedto an end of a shaft 55 a, 56 a for the support and rotation of thecorresponding pre-stretching roller 55, 56, and provided with aneccentric portion 97 a, 98 a that is suitable to engage the transverseseat 95 a, 96 a of the respective bush 95, 96.

In order to simplify the mounting of the unwinding unit 50 on thesupporting unit 60, eccentric portions 97 a, 98 a are progressivelyinserted in the respective transverse seats 95 a, 96 a, the latter havea tapered side opening or promoting portion 95 b, 96 b beingsubstantially “V”-shaped. Furthermore, the eccentric portions 97 a, 98 aof the follower members 97, 98 are provided with a pair of wheels 99,for example roller bearings, which can slide by rotating on oppositeside walls of the transverse seats 95 a, 96 b. In the assembledconfiguration A, the eccentric portions 97 a, 98 a are completely housedwithin the transverse seats 95 a, 96 b. The bushes 95, 96, rotated bythe motor around the respective longitudinal axes, impart with therespective transverse seats 95 a, 96 a on the wheels 99, and thereforeon the eccentric pins 97, 98, a torque or moment of forces that rotatesthe pre-stretching rollers 55, 56.

As illustrated in the FIGS. 32 to 34, the wrapping machine 10 caninclude a replacement apparatus 20 capable of automatically replacing anunwinding unit 50 of the unwinding apparatus 30 associated with theabove-mentioned machine, in particular, capable of dismantling andreceiving, from a supporting unit 60 fixed to the movement mechanism100, an unwinding unit 50 to be replaced or capable of transferring andmounting a new or replacement unwinding unit 50 on the supporting unit60. The supporting unit to be replaced is a unit having an exhaustedfilm reel 3 or with the above-mentioned film that is broken, damaged, orjammed. The replacement unwinding unit is a unit provided with a newfilm reel, in which the initial flap of film 4 unwound from the reel isretained by the gripping device 59 and wound around the pre-stretching55, 56 and guide 57 rollers.

The replacement apparatus 20 includes, for example, shuttles 11, 12 thatare movable on guide 2 along a path P, and arranged to house at leastone unwinding unit 50 to be replaced and to be dismantled from thewrapping machine 10 and to support at least one replacement unwindingunit 50 to be mounted on the wrapping machine 10.

The shuttles 11, 12 include transfer devices 15 suitable for receivingand supporting at least one unwinding unit 50, and movable between aretracted position and an extended position along the operatingdirection T to allow the shuttles 11, 12 to selectively dismantle andreceive an unwinding unit 50 to be replaced or to transfer and mount areplacement unwinding unit 50.

The operating direction T along which the transfer device 15 is moved issubstantially radial to a circular winding trajectory of the film 4around the load L and transverse, in particular, orthogonal, to the pathP.

The shuttles include a plurality of shuttles 11, 12, for example two, asin the illustrated embodiment, which are mutually connectable so as toform at least one convoy of shuttles, each shuttle including arespective transfer device 15 for supporting and moving at least onerespective unwinding unit 50.

Each shuttle 11, 12 includes a carriage 13 provided with sliding wheelsand configured to engage and slide on the guide 2. The transfer deviceis slidably connected to the carriage 13, including a transfer platform15 fixed by telescopic guides to end portions of the above-mentionedcarriage 13 so as to be movable between the retracted position and theextended position along the operating direction T. The replacement orchanging procedure of an unwinding unit 50 to be replaced, mounted onboard of the wrapping machine 10, with a replacement unwinding unit 50located on the shuttles 11, 12 in an initial step, moves the shuttles11, 12 from a inactive position N1, outside a working zone W of thewrapping machine 10 (FIG. 32), to a first operating position F1 withinthe working zone W (FIG. 34). In the first operating position the freeshuttle is precisely under the rotating ring 101, while the transferdevice 15 is in the extended position to receive the unwinding unit 50to be replaced.

The rotating ring 101 of the wrapping machine 10 is then verticallylowered to rest the unwinding unit 50 to be replaced on the platform ofthe transfer device 15 of the shuttle. The transfer device 15 is thenactuated in the retracted position to allow the unwinding unit 50 to bereplaced to be disengaged and dismantled from the supporting unit 60that is fixed to the rotating ring 101.

The shuttles 11, 12 are moved to a second operating position, in whichthe shuttle provided with unwinding units 50 is at the supporting unit60. At this point, the transfer device 15 of the shuttle 12 is moved inthe extended position in order to mount the replacement unwinding unit50 on the supporting unit 60. More precisely, the first coupling device58 is slidably inserted into the second coupling device 68. In asuccessive operating wrapping step, the second transmission 72 engagesthe first transmission 71 to allow the motors 81, 82 to rotate thepre-stretching rollers 55, 56. Once the unwinding unit 50 has beenmounted on the supporting unit 60, the rotating ring 101 is verticallymoved to disengage the unwinding unit 50 from the shuttle 12.

Owing to the replacement apparatus 20, it is possible to automatically,rapidly and efficiently replace an unwinding unit 50 in a wrappingmachine 10, without any intervention by operators. Furthermore, thewrapping machine 10 provided with the apparatus of the invention 20 canoperate in a completely automatized manner, without the intervention ofoperators, for prolonged work shifts, since the shuttles 11, 12 cansupport, and therefore replace, a plurality of unwinding unit 50arranged on respective shuttles.

A number of substitute unwinding units 50 can be provided for, in orderto allow prolonged work shifts of the machine, without unduly affectingthe whole cost of the machine itself.

FIG. 38 illustrates an embodiment of the unwinding apparatus 30 of theinvention associated with a wrapping machine 10 of the rotating table,or rotary platform, type. In this wrapping machine 10, the supportingunit 60 of the apparatus 1 is mounted on a first wrapping carriage 201that is vertically movable along a fixed first column 202, while theload L is rotated around the wrapping axis Z by the rotating table 203on which it is located. The first wrapping carriage 201 and the firstcolumn 202 act as a second movement mechanism 200 that is arranged formoving the supporting unit 60 and the unwinding unit 50 with respect tothe load L.

Such an embodiment of the unwinding apparatus 30 differs from theabove-described embodiment in that the motor 281 of the driving assembly70 includes a motor mounted on the supporting unit 60. Such motor 281directly drives the first transmission 71 which engages and moves thesecond transmission 72 of the pre-stretching rollers 54, 55.

Also in this case, the wrapping machine 10 is provided with areplacement apparatus 20 including shuttles 11, 12 suitable to dismantleand receive from the wrapping machine 10 an unwinding unit 50 to bereplaced, and thus, to transfer and mount a replacement unwinding unit50 on the wrapping machine 10.

FIG. 39 illustrates a further version of the unwinding apparatus 30 ofthe invention associated with a wrapping machine 10 of the doublerotating arm type. In this wrapping machine, two unwinding devices 1 areprovided, each of which is associated with a respective rotating arm402. In particular, the supporting unit 60 of each apparatus 1 ismounted on a third wrapping carriage 401 that is vertically movablealong a respective vertical arm 402, the latter being fixed to a rotarycross beam 404, so as to rotate around the wrapping axis and the load L.

The third carriages 401, the vertical arms 402, and the rotary crossbeam 404 act as a fourth movement mechanism 400 that is arranged formoving the supporting unit 60 and the unwinding unit 50 with respect tothe load L.

The driving assembly 70 of each apparatus 1 includes a pair of motors481, 482 that are fixed to the respective supporting unit 60 andarranged for driving separately and independently the pre-stretchingrollers by the first transmission 71 and the second transmission 72.

The replacement apparatus 20 allows the simultaneous replacement of thetwo unwinding units 50 mounted on the two vertical arms 402. Thereplacement apparatus is provided with guides 2 including two beamsalong which respective shuttles 11, 12 move. The guide is arranged todismantle from the wrapping machine 10 and to receive an unwinding unit50 to be replaced or to transfer and mount a new unwinding unit 50 onthe wrapping machine 10.

Therefore, the unwinding apparatus 30 of the invention can beefficiently and advantageously employed on different types of wrappingmachines, since the driving assembly 70, associated with the supportingunit 60 fixed to the movement mechanisms 100, 200, 400 of the wrappingmachine includes a motor that can be located directly on theabove-mentioned supporting unit (for example, in the case of rotatingarm or rotating table wrapping machines) or onto a frame of the wrappingmachine (for example rotating ring wrapping machines).

1-32. (canceled)
 33. Unwinding apparatus for an wrapping machine,comprising (a) a support unit connected with the wrapping machine; (b)an unwinding unit removably connected with said support unit, saidunwinding unit including a reel of film and a plurality of rollers forunwinding said filth froth said reel and winding it around a load, saidrollers including first and second pre-stretching rollers for unwindingand pre-stretching said film; and (c) a driving assembly connected withsaid support unit for rotating said pre- stretching rollers. 34.Apparatus as defined in claim 33, wherein said driving assembly includesat least one motor and first and second transmissions, said firsttransmission being driven by said motor and said second transmissionbeing driven by said first transmission for rotating said pre-stretchingrollers.
 35. Apparatus as defined in claim 34, wherein said firsttransmission includes a pair of flexible elements driven by said atleast one motor and said second transmission includes a pair wheelsconnected with respective pre-stretching rollers, each flexible elementengaging and rotating a respective wheel.
 36. Apparatus as defined inclaim 34, wherein said first transmission includes a pair of movablemembers rotated by said at least one motor and said second transmissiona pair of followers Connected with respective pre-stretching rollers,each movable member engaging and rotating a respective follower. 37.Apparatus as defined in claim 34, wherein said motors are mounted onsaid support unit and connected with said first transmission. 38.Apparatus as defined in claim 34, and wherein said wrapping machineincludes a frame, said motors being connected with said frame and saiddriving assembly includes a third transmission connecting said firsttransmission with said at least one motor.
 39. Apparatus as defined inclaim 33, and further comprising movement means connected with thewrapping machine for moving said support unit and said unwinding unitcoupled therewith with respect to the load.
 40. Apparatus as defined inclaim 33, wherein said rollers include at least one guide roller forguiding said film from said reel to said pre-stretching rollers and fromsaid pre-stretching rollers toward said load to define a wrapping angleof said film greater than 180°.
 41. Apparatus as defined in claim 33,wherein said pre-stretching rollers are adjustably connected with aframe of the wrapping machine to vary the axes between saidpre-stretching rollers.
 42. Apparatus as defined in claim 33, whereinsaid unwinding unit includes a first coupling device and said supportunit includes a second coupling device, said first and second couplingdevices operating in a horizontal operating direction.
 43. Apparatus asdefined in claim 42, wherein said first coupling means comprises a setof rails and said second coupling means comprises a seat for receivingsaid set of rails in a coupling position in which said unwinding unit isengaged with and supported by said support unit.
 44. A wrapping machinefor wrapping a load with a film, comprising movement means forsupporting and moving an unwinding apparatus as defined in claim 33relative to the load.
 45. A wrapping machine as defined in claim 44, andfurther comprising a replacement apparatus for dismantling and receivingfrom said support unit an unwinding unit to be replaced and fortransferring and mounting on said support unit a replacement unwindingunit, said support unit being connected with said movement means.